Field
The present disclosure relates generally to image data. Aspects may be incorporated into cameras and may be used, e.g., to generate images for ultra high definition (UHD) displays.
Background
Ultra high definition (UHD) displays are used in a variety of applications, including televisions, personal computers and tablets, smart phones, and camera viewfinders. Reduced sharpness in such displays may occur due to relative motion of objects in the image. For camera viewfinders, a “motion blur” effect is caused by relatively long exposure time of each image (20 ms in a 50 Hz system and 16.6 ms in a 59.94 Hz system). As an object moves during an image exposure of a camera imager, details are lost as the object is spread over multiple pixels. One solution is to increase the number of frames that are being captured per second, reducing the exposure time of each individual frame as a consequence. All of these frames at the higher frame rate may be transmitted to the display to deliver sharper images but with great expense of signal bandwidth. In addition, as the camera generates more images per second, the amount of photons received by the image sensor per image diminishes, resulting in a lower light sensitivity of the camera and lower signal to noise ratio.
As an alternative to creating more images per second, the exposure could also be reduced by using an electronic shutter, to keep the number of frames per second the same and only shorten the exposure time of each image. This reduces the motion blur (as there's less time for movement) but also leads to a lower light sensitivity and in addition introduces a disturbing strobe effect (i.e., “judder”). Using this approach effectively produces zero exposure (i.e., blackness) within the frame when the shutter is closed, creating a gap between the images. The human eye will attempt to ‘track’ the object motion from frame to frame. A ball that flies through the air, could be razor sharp in each image, but as the camera image sensors only have captured short exposure moments, the visual trajectory information is lost and the ball seems to jump through the scene, lacking smoothness of motion. As the human visual system is ‘trained’ to track objects, this leads to a distracted viewing experience.